Dolforwyn Castle was built by Llywelyn the Last in 1273. Llywelyn ap Gruffudd built the castle as a snub to the authority of the English crown. The castle fell to Edward I just four years later, and was little used thereafter. It was in ruins by the 1390s. The ruins of the castle remain today.
From www.york.ac.uk: "Llywelyn ap Gruffydd was the last independent
Prince of Wales and he controlled large areas of north-west and central
Wales until his death in 1282. A major opponent in central Wales was Roger
Mortimer of Wigmore (Herefordshire) and it seems likely that his raids
into Welsh-held territory forced Llywelyn to build the castle at Dolforwyn.
It was under construction in 1272-3 while Edward I was absent on crusade.
It is not known how far the building programme had reached when it was
beseiged and captured by the English in April 1277; the attacking force
was led by Roger Mortimer (later earl of the March) and Henry de Lacy,
earl of Lincoln. Some new work was done to repair the war damage, using
grey siltstone and hard white lime mortar. The castle was occupied by the
Mortimer family for about a hundred years, but by 1398 it was `ruinous
and worth nothing'. After that date it seems to have been left to decay."